Direct acting sympathomimetics – Clonidine MCQs With Answer

Direct acting sympathomimetics – Clonidine MCQs With Answer

Clonidine is a centrally acting alpha-2 adrenergic agonist widely studied in pharmacology and therapeutics. This concise introduction highlights clonidine’s mechanism of action, receptor selectivity, pharmacokinetics, clinical uses (hypertension, ADHD, opioid withdrawal, analgesia), common formulations (oral, transdermal, epidural), key adverse effects (sedation, dry mouth, bradycardia, rebound hypertension), and important drug interactions. B. Pharm students should understand clonidine’s central sympatholytic effects, monitoring requirements, dose adjustments in renal impairment, and management of withdrawal or overdose. These MCQs emphasize both conceptual and applied knowledge to help you master clonidine for exams and clinical practice. Now let’s test your knowledge with 50 MCQs on this topic.

Q1. Which receptor subtype does clonidine primarily stimulate to produce its antihypertensive effect?

• Beta-1 adrenergic receptors
• Alpha-1 adrenergic receptors
• Alpha-2 adrenergic receptors
• Muscarinic M2 receptors

Correct Answer: Alpha-2 adrenergic receptors

Q2. Clonidine lowers blood pressure mainly by which central mechanism?

• Inhibition of baroreceptor activity in the carotid sinus
• Stimulation of central alpha-2 receptors reducing sympathetic outflow
• Direct vasodilation of peripheral arterioles via nitric oxide
• Blockade of angiotensin II receptors

Correct Answer: Stimulation of central alpha-2 receptors reducing sympathetic outflow

Q3. Which of the following clinical uses of clonidine is correct?

• First-line therapy for acute myocardial infarction
• Treatment of chronic hypertension, ADHD, and opioid withdrawal symptoms
• Primary therapy for bacterial endocarditis
• Antiplatelet agent in stroke prevention

Correct Answer: Treatment of chronic hypertension, ADHD, and opioid withdrawal symptoms

Q4. Which formulation of clonidine provides sustained transdermal systemic delivery typically changed weekly?

• Oral immediate-release tablet
• Intravenous bolus injection
• Transdermal patch
• Nasal spray

Correct Answer: Transdermal patch

Q5. Which effect is a common adverse reaction to clonidine therapy?

• Excessive salivation
• Tachycardia and hyperactivity
• Dry mouth and sedation
• Increased appetite and weight gain

Correct Answer: Dry mouth and sedation

Q6. Abrupt discontinuation of clonidine most commonly causes which dangerous phenomenon?

• Prolonged bradycardia without hypertension
• Rebound hypertension due to sympathetic surge
• Persistent sedation and coma
• Acute pulmonary edema

Correct Answer: Rebound hypertension due to sympathetic surge

Q7. In clonidine overdose presenting with severe bradycardia and hypotension, which is an appropriate acute management step?

• Immediate high-dose beta blocker
• Administration of intravenous atropine for bradycardia
• Give oral clonidine to increase absorption
• Administer benzodiazepines to increase heart rate

Correct Answer: Administration of intravenous atropine for bradycardia

Q8. Which drug class can reduce the antihypertensive efficacy of clonidine by blocking its central effects?

• Tricyclic antidepressants (TCAs)
• ACE inhibitors
• Loop diuretics
• Calcium channel blockers

Correct Answer: Tricyclic antidepressants (TCAs)

Q9. Clonidine’s initial peripheral vascular effect after rapid intravenous administration may include:

• Immediate powerful hypotension without rebound
• Transient peripheral vasoconstriction and brief hypertension
• Inhibition of platelet aggregation
• Direct myocardial contractility increase

Correct Answer: Transient peripheral vasoconstriction and brief hypertension

Q10. Which adverse metabolic effect is associated with alpha-2 adrenergic stimulation by clonidine?

• Increased insulin secretion leading to hypoglycemia
• Inhibition of insulin release leading to hyperglycemia
• Marked hyperlipidemia within hours
• Enhanced glycogen synthesis in the liver

Correct Answer: Inhibition of insulin release leading to hyperglycemia

Q11. For which of the following indications is epidural clonidine most appropriately used?

• As a sole agent for induction of general anesthesia
• Adjunct to regional anesthesia to enhance analgesia
• First-line treatment for bacterial meningitis
• Routine prophylaxis for deep vein thrombosis

Correct Answer: Adjunct to regional anesthesia to enhance analgesia

Q12. Which of the following statements about clonidine pharmacokinetics is true?

• It is poorly lipid soluble and does not cross the blood–brain barrier
• It is highly lipophilic and readily penetrates the central nervous system
• It is exclusively metabolized to inactive metabolites and not renally excreted
• It has a half-life of several seconds, requiring continuous infusion

Correct Answer: It is highly lipophilic and readily penetrates the central nervous system

Q13. Which receptor subtype in the spinal cord mediates clonidine’s analgesic action?

• Alpha-1 adrenergic receptors
• Beta-2 adrenergic receptors
• Alpha-2 adrenergic receptors
• NMDA receptors

Correct Answer: Alpha-2 adrenergic receptors

Q14. Which precaution is most important when prescribing clonidine to a patient with renal impairment?

• No precaution is needed since clonidine is not renally cleared
• Reduce dose or extend dosing interval due to renal excretion
• Increase the dose because renal failure decreases effect
• Switch to a drug with the same half-life as creatinine clearance

Correct Answer: Reduce dose or extend dosing interval due to renal excretion

Q15. Which of the following agents is a more selective alpha-2 agonist often compared with clonidine for sedation in ICU settings?

• Phenylephrine
• Dexmedetomidine
• Norepinephrine
• Isoprenaline

Correct Answer: Dexmedetomidine

Q16. Which adverse cardiovascular effect is clonidine most likely to cause during chronic therapy?

• Persistent tachyarrhythmias
• Bradycardia and orthostatic hypotension
• Acute coronary vasospasm
• Sustained increases in left ventricular contractility

Correct Answer: Bradycardia and orthostatic hypotension

Q17. Which agent would be a pharmacologic antagonist to reverse clonidine’s effects in experimental settings?

• Yohimbine (an alpha-2 antagonist)
• Propranolol (a beta blocker)
• Phenylephrine (an alpha-1 agonist)
• Atropine (a muscarinic antagonist)

Correct Answer: Yohimbine (an alpha-2 antagonist)

Q18. Which central nervous system adverse effect must patients be warned about when starting clonidine?

• Insomnia and agitation
• Excessive sedation and drowsiness
• Hyperactivity and increased concentration
• Severe auditory hallucinations

Correct Answer: Excessive sedation and drowsiness

Q19. In management of severe clonidine withdrawal with hypertensive crisis, the most recommended immediate action is:

• Administer a systemic beta-agonist
• Reinstate clonidine or give an alpha-adrenergic blocker
• Give large doses of benzodiazepines only
• Immediate hemodialysis is mandatory

Correct Answer: Reinstate clonidine or give an alpha-adrenergic blocker

Q20. Which patient population is clonidine commonly used in as adjunctive therapy for attention deficit hyperactivity disorder (ADHD)?

• Elderly patients only
• Pediatric patients and adolescents as adjunct or alternative
• Patients with severe active infections
• Pregnant women as first-line ADHD therapy

Correct Answer: Pediatric patients and adolescents as adjunct or alternative

Q21. Which of the following is an important monitoring parameter for a patient starting clonidine?

• Serial arterial blood gas measurements
• Regular monitoring of blood pressure and heart rate
• Frequent liver function tests every 6 hours
• Continuous EEG monitoring

Correct Answer: Regular monitoring of blood pressure and heart rate

Q22. Clonidine’s structural class is best described as which of the following?

• Sulfonylurea derivative
• Imidazoline derivative
• Beta-lactam antibiotic
• Calcium channel blocker

Correct Answer: Imidazoline derivative

Q23. Which of the following drug interactions with clonidine can increase the risk of severe bradycardia?

• Concurrent use of antacids
• Concomitant beta-blocker therapy
• Co-administration with oral contraceptives
• Use with magnesium supplements

Correct Answer: Concomitant beta-blocker therapy

Q24. Which statement about clonidine’s effect on catecholamine levels is correct?

• It increases plasma norepinephrine by stimulating release
• It decreases plasma catecholamines by reducing sympathetic tone
• It has no effect on catecholamine concentrations
• It converts norepinephrine to epinephrine in peripheral tissues

Correct Answer: It decreases plasma catecholamines by reducing sympathetic tone

Q25. Which of the following clinical situations is clonidine particularly helpful in treating?

• Acute bacterial infection causing fever
• Management of autonomic hyperactivity during opioid withdrawal
• Immediate reversal of anticoagulation
• Treatment of acute ischemic stroke within minutes

Correct Answer: Management of autonomic hyperactivity during opioid withdrawal

Q26. What effect does clonidine have on the baroreceptor reflex?

• It enhances baroreceptor sensitivity leading to tachycardia
• It blunts sympathetic outflow and modulates baroreceptor-mediated responses
• It causes complete loss of baroreceptor function permanently
• It directly stimulates baroreceptor firing to increase blood pressure

Correct Answer: It blunts sympathetic outflow and modulates baroreceptor-mediated responses

Q27. Which of the following symptoms would most likely indicate clonidine toxicity in a patient?

• Hyperreflexia and muscle spasms
• Profound hypotension, bradycardia, and severe sedation
• Severe hypertension and tachycardia only
• Acute hyperglycemic coma

Correct Answer: Profound hypotension, bradycardia, and severe sedation

Q28. How does clonidine affect gastrointestinal motility and secretions commonly?

• Markedly increases gastric acid secretion
• Often causes dry mouth and may reduce gastrointestinal secretions
• Leads to severe diarrhea in most patients
• Directly stimulates pancreatic enzyme release

Correct Answer: Often causes dry mouth and may reduce gastrointestinal secretions

Q29. Compared to methyldopa, clonidine is best characterized by which feature?

• Clonidine is slower in onset and reserved for pregnancy only
• Clonidine has a more rapid onset and is more potent in lowering central sympathetic tone
• Methyldopa is an alpha-2 agonist and clonidine is a beta blocker
• Both drugs are identical in mechanism and clinical profile

Correct Answer: Clonidine has a more rapid onset and is more potent in lowering central sympathetic tone

Q30. Which adverse psychiatric effect has been reported with clonidine therapy and should be monitored?

• Improved mood and euphoria in all patients
• Potential for depression or mood changes in some patients
• Guaranteed prevention of suicidal ideation
• Onset of schizophrenia-like psychosis in majority

Correct Answer: Potential for depression or mood changes in some patients

Q31. Which of the following best explains clonidine’s role in treating menopausal hot flashes?

• It blocks estrogen receptors directly
• It reduces central sympathetic hyperactivity that contributes to vasomotor symptoms
• It acts as a selective serotonin reuptake inhibitor
• It increases peripheral catecholamine release

Correct Answer: It reduces central sympathetic hyperactivity that contributes to vasomotor symptoms

Q32. Regarding pregnancy and lactation, which statement about clonidine is accurate?

• Clonidine is known to be completely safe and is first-line during pregnancy
• Clonidine crosses the placenta and should be used with caution in pregnancy
• Clonidine does not cross into breast milk and is safe for nursing mothers
• Clonidine is a proven teratogen and is absolutely contraindicated

Correct Answer: Clonidine crosses the placenta and should be used with caution in pregnancy

Q33. Which physiologic effect is expected shortly after a therapeutic dose of clonidine?

• Increase in sympathetic tone and tachycardia
• Decrease in peripheral vascular resistance and reduced heart rate
• Marked increase in myocardial contractility
• Stimulation of renin release leading to sodium retention

Correct Answer: Decrease in peripheral vascular resistance and reduced heart rate

Q34. Which laboratory parameter is most likely to show a change with clonidine therapy?

• Significant persistent elevation of serum potassium
• Reduced plasma catecholamine (norepinephrine) levels
• Marked rise in serum creatine kinase
• Immediate increase in leukocyte count

Correct Answer: Reduced plasma catecholamine (norepinephrine) levels

Q35. For a B. Pharm student, which pharmacodynamic property explains clonidine’s ability to reduce sympathetic neurotransmission?

• Activation of presynaptic alpha-2 receptors inhibits norepinephrine release
• Activation of presynaptic beta receptors increases norepinephrine release
• Inhibition of monoamine oxidase in synaptic clefts
• Blockade of sodium channels in autonomic ganglia

Correct Answer: Activation of presynaptic alpha-2 receptors inhibits norepinephrine release

Q36. Which symptom is most suggestive of clonidine withdrawal in a patient who stopped therapy abruptly?

• Bradycardia lasting weeks
• Marked rebound hypertension often with tachycardia and agitation
• Gradual return of normal blood pressure without symptoms
• Immediate weight loss and hypothermia

Correct Answer: Marked rebound hypertension often with tachycardia and agitation

Q37. When used with tricyclic antidepressants, clonidine’s antihypertensive effect is often:

• Potentiated dramatically
• Antagonized or reduced
• Unaffected
• Converted into a vasopressor effect

Correct Answer: Antagonized or reduced

Q38. Which of the following best describes clonidine’s renal excretion profile?

• Clonidine is almost entirely metabolized and not excreted renally
• A significant proportion is excreted unchanged in the urine, requiring dose adjustment in renal impairment
• It is eliminated only by biliary excretion
• It undergoes rapid renal clearance independent of renal function

Correct Answer: A significant proportion is excreted unchanged in the urine, requiring dose adjustment in renal impairment

Q39. Which cardiovascular monitoring is essential when initiating clonidine in elderly patients?

• Continuous internal jugular venous pressure monitoring
• Frequent blood pressure and pulse checks to detect hypotension and bradycardia
• Serial echocardiograms daily
• 24-hour Holter every hour

Correct Answer: Frequent blood pressure and pulse checks to detect hypotension and bradycardia

Q40. Which of the following is an approved and commonly used indication of clonidine in pediatrics?

• Treatment of bacterial infections
• Adjunctive therapy for attention deficit hyperactivity disorder (ADHD)
• Primary anticonvulsant for epilepsy
• Routine vaccine adjuvant

Correct Answer: Adjunctive therapy for attention deficit hyperactivity disorder (ADHD)

Q41. Which of the following describes an important counseling point for patients using clonidine transdermal patches?

• Patches can be applied to broken or inflamed skin for better absorption
• Apply to clean, dry, intact skin and replace at prescribed intervals (typically weekly)
• Patches should be alternated hourly to different sites
• They must be removed only when showers are taken

Correct Answer: Apply to clean, dry, intact skin and replace at prescribed intervals (typically weekly)

Q42. Why might clonidine be used as adjunctive therapy in chronic pain management?

• It increases peripheral nociceptor activation
• Activation of spinal alpha-2 receptors produces analgesia and reduces opioid requirements
• It directly dissolves inflammatory mediators at pain sites
• It enhances NMDA receptor-mediated pain transmission

Correct Answer: Activation of spinal alpha-2 receptors produces analgesia and reduces opioid requirements

Q43. Which sign would argue against clonidine therapy in a hypertensive patient?

• Baseline resting heart rate of 60 bpm
• Presence of severe bradycardia or high-grade atrioventricular block
• Well-controlled diabetes without complications
• Mild chronic kidney disease with adjusted dosing

Correct Answer: Presence of severe bradycardia or high-grade atrioventricular block

Q44. Which of the following best explains why clonidine can cause rebound sympathetic activity when stopped abruptly?

• Permanent destruction of adrenergic neurons during therapy
• Upregulation and increased sensitivity of peripheral adrenergic receptors after chronic central suppression
• Accumulation of clonidine in adipose tissue causing delayed release
• Formation of antibody–drug complexes that stimulate catecholamine release

Correct Answer: Upregulation and increased sensitivity of peripheral adrenergic receptors after chronic central suppression

Q45. Which of the following best describes clonidine’s effect on respiratory drive at therapeutic doses?

• Pronounced respiratory depression similar to opioids
• Minimal respiratory depression compared with opioids
• Complete suppression of the medullary respiratory center
• Marked stimulation of ventilation leading to hyperventilation

Correct Answer: Minimal respiratory depression compared with opioids

Q46. Which organ system is primarily responsible for metabolizing clonidine?

• Renal excretion with partial hepatic metabolism
• Only pulmonary metabolism
• Complete intestinal metabolism without renal involvement
• Exclusively biliary excretion

Correct Answer: Renal excretion with partial hepatic metabolism

Q47. Which therapeutic advantage does clonidine transdermal delivery offer over oral immediate-release dosing?

• Faster peak plasma concentration within seconds
• Improved steady plasma levels with once-weekly dosing and better compliance
• Complete avoidance of systemic side effects
• Ability to deliver unlimited doses without toxicity

Correct Answer: Improved steady plasma levels with once-weekly dosing and better compliance

Q48. Which of the following is a correct statement differentiating clonidine from direct acting sympathomimetics?

• Clonidine is a central sympatholytic, whereas direct sympathomimetics stimulate peripheral adrenergic receptors
• Clonidine directly activates beta-adrenergic receptors like isoproterenol
• Direct sympathomimetics and clonidine have identical mechanisms of action
• Clonidine is a muscarinic agonist while sympathomimetics are not

Correct Answer: Clonidine is a central sympatholytic, whereas direct sympathomimetics stimulate peripheral adrenergic receptors

Q49. Which adverse sexual side effect has been associated with clonidine use?

• Increased libido in all patients
• Potential sexual dysfunction including erectile dysfunction
• Guaranteed improvement in fertility
• Immediate and progressive priapism in all males

Correct Answer: Potential sexual dysfunction including erectile dysfunction

Q50. For safe discontinuation of clonidine after chronic therapy, the recommended strategy is:

• Abrupt stopping to avoid prolonged side effects
• Gradual tapering or substituting therapy to prevent rebound hypertension
• Doubling the dose every other day before stopping
• Switching immediately to high-dose beta blockers without taper

Correct Answer: Gradual tapering or substituting therapy to prevent rebound hypertension

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com